This invention relates generally to phased array antennas and more particularly to the compensation of beam pointing errors resulting from frequency and temperature changes.
In airborne and ground based phased array antenna systems driven by a series-fed power divider and operating over a selected range of frequencies, beam pointing errors and undesired antenna sidelobes are known to be generated as a function of the expansion and contraction of the aperture as a function of temperature and more particularly over the range from -50.degree. C. to +70.degree. C. when operating at a predetermined frequency. Phased errors resulting from expansion and contraction of the manifold of the power divider are also known to exist as a result of temperature changes. Heretofore, compensation for these errors was accomplished by constructing the antenna components from relatively expensive material having a low temperature coefficient of expansion, a typical example being invar, an alloy of iron and nickel. This mechanical approach has been found to be relatively costly and, at most, an approximation.
Accordingly, it is an object of the present invention to provide an improvement in phased array antenna systems.
It is a further object of the invention to provide an improvement in the compensation for pointing angle errors introduced by dimensional changes of the antenna beam forming structure.
It is yet another object of the invention to provide electrical compensation for pointing errors and sidelobes due to temperature in a phased array antenna.
And it is still a further object of the invention to electronically shift the antenna beam forming angle to compensate for pointing angle errors and sidelobes introduced by dimensional changes of the phase antenna beam forming structure due to temperature changes when operated over a relatively large frequency band.